1. Field of the Invention
This invention relates to semiconductor devices and more particularly to masks for patterning semiconductor devices.
2. Description of Related Art
U.S. Pat. No. 5,798,303 of Clampitt for "Etching Method for Use in Fabrication of Semiconductor Devices" describes an oxygen plasma descum method using oxygen to remove a polymer material by etching using "a descum step 14, such as, for example, an oxygen plasma descum, to selectively etch the blocking material from the substantially vertical sidewall of the device . . . ", Col. 3, lines 54-65. Referring to Col. 5, 26-41, polymer blocking material 64, 66 forms over sidewall spacers 46/52 during the removal of conductive material 60 which is not protected by the photoresist 62. The blocking material 64/66 must be removed from the device. An inert carrier such as helium can be incorporated with the oxygen in the plasma. (Col. 6, lines 19-18.) A fluorine containing gas and oxygen plasma can be used (Col. 7, lines 7-17.)
U.S. Pat. No. 5,637,186 of Liu et al. for "Method and Monitor Testsite Pattern for Measuring Critical Dimension Openings" describes measurement of After Development Inspection (ADI) and After Etching Inspection (AEI) for layers of photoresist, see Col. 4, lines 49-67.
U.S. Pat. No. 4,800,251 of Matsuoka for "Apparatus for Forming a Resist Pattern" U.S. Pat. No. 5,200,360 of Bradbury et al. for "Method for Reducing Selectivity Loss in Selective Tungsten Deposition", and U.S. Pat. No. 5,259,924 of Mathews et al. for "Integrated Circuit Fabrication Process to Reduce Critical Dimension During Etching" show plasma descum methods.
U.S. Pat. No. 4,529,860 of Robb for "Plasma Etching of Organic Materials" shows a plasma etching (descum) process.
U.S. Pat. No. 4,959,326 of Roman et al. for "Fabricating T-Gate MESFETS Employing Double Exposure, Double Develop Techniques" teaches a double exposure technique to improve photo accuracy.